US7005247B1ExpiredUtility

Controlled selectivity etch for use with optical component fabrication

65
Assignee: KOTUSA INCPriority: Sep 6, 2002Filed: Jan 15, 2003Granted: Feb 28, 2006
Est. expirySep 6, 2022(expired)· nominal 20-yr term from priority
Inventors:Joan FongWei QianDawei ZhengZhian ShaoLih-Jou ChungXiaoming Yin
G02B 6/136G02B 6/12011G02B 2006/12097G02B 6/12016G02B 6/138G02B 2006/121
65
PatentIndex Score
9
Cited by
102
References
32
Claims

Abstract

A method of fabricating an optical component includes forming a mask on an optical component precursor. The method also includes etching through at least a portion of the mask so as to etch an underlying medium concurrently with remaining mask and transfer a feature of an upper surface of the mask onto an upper surface of the underlying medium. The etch can be configured such that a ratio of the underlying medium etch rate to the mask etch rate is less than about 1.5:1. In some instances, the underlying medium is silicon and the mask is a photoresist.

Claims

exact text as granted — not AI-modified
1. A method of fabricating an optical component, comprising:
 forming a mask on an optical component precursor having a ridge with a horizontally tapered region, the mask including a vertical taper positioned over the horizontally tapered region of the ridge; 
 etching through at least a portion of the mask so as to etch the ridge concurrently with remaining mask and transfer the vertical taper to the underlying ridge, a ratio of the ridge etch rate to the mask etch rate being less than 1.5:1. 
 
     
     
       2. The method of  claim 1 , wherein the ratio is between 0.8:1 and 1.2:1. 
     
     
       3. The method of  claim 1 , wherein the ratio is between 0.9:1 and 1.1:1. 
     
     
       4. The method of  claim 1 , wherein the mask is positioned over a rough surface on the ridge and a surface of the mask positioned over the rough surface is smoother than the rough surface. 
     
     
       5. The method of  claim 4 , wherein etching through at least a portion of the mask includes etching through at least a portion of the mask positioned over the rough surface so as to smooth the rough surface. 
     
     
       6. The method of  claim 1 , wherein etching through at least a portion of the mask includes employing an etchant including a Fluorine containing gas. 
     
     
       7. The method of  claim 1 , wherein etching through at least a portion of the mask includes employing an etchant including a Fluorine containing gas and a second component having the formula C x H y F z  where X=1 or greater, Y=0 or greater, and Z=1 or greater, the second component being different from the Fluorine containing gas. 
     
     
       8. The method of  claim 7 , wherein a molar ratio of Fluorine containing gas to second component in the etchant is in the range of 0.005:1 to 0.25:1. 
     
     
       9. The method of  claim 1 , wherein etching through at least a portion of the mask includes employing an etchant including a Fluorine containing gas and a component selected from the group consisting of CF 4 , CHF 3 , CH 2 F 2 , C 2 F 6 , C 4 F 6 , and C 4 F 8 . 
     
     
       10. The method of  claim 1 , wherein etching the optical component precursor includes employing an etchant including SF 6  and CF 4 . 
     
     
       11. The method of  claim 1 , wherein etching the optical component precursor includes employing an etchant including CF 4 . 
     
     
       12. The method of  claim 1 , wherein etching the optical component precursor includes applying an etchant to the optical component precursor at an RF DC bias power of about 100 W to 140 W. 
     
     
       13. The method of  claim 1 , wherein etching the optical component precursor includes applying an etchant to the optical component precursor at a pressure in a range of 1–20 mTorr. 
     
     
       14. The method of  claim 1 , wherein etching the optical component precursor includes applying an etchant to the optical component precursor at a pressure in a range of 1 to 10 mTorr. 
     
     
       15. The method of  claim 1 , wherein the mask is a photoresist and the ridge is silicon. 
     
     
       16. The method of  claim 1 , wherein the mask is a photoresist and the ridge is polysilicon. 
     
     
       17. A method of fabricating an optical component, comprising:
 forming a mask on an optical component precursor; 
 etching through at least a portion of the mask so as to etch a medium underlying the mask concurrently with remaining mask and transfer a feature of an upper surface of the mask onto an upper surface of the underlying medium, the etch employing an etchant that includes a Fluorine containing gas and one or more second components having the general formula C x H y F z  where 
 
       X=1 or greater, Y=0 or greater, and Z=1 or greater and applied so as to provide a ratio of medium etch rate to mask etch rate in a range of 0.9:1 to 1.1:1. 
     
     
       18. The method of  claim 17 , wherein the mask includes a vertical taper and etching through at least a portion of the mask substantially transfers the vertical taper to the underlying medium. 
     
     
       19. The method of  claim 18 , wherein the underlying medium includes a ridge that tapers horizontally and the vertical taper of the mask is positioned over the horizontally tapered region of the underlying medium and the etch substantially transfers the vertical taper to the underlying ridge. 
     
     
       20. The method of  claim 18 , wherein the vertical taper of the mask is positioned over a region of an optical component precursor where a mode transformer is to be formed on the optical component precursor. 
     
     
       21. The method of  claim 17 , wherein the underlying medium includes a rough upper surface and an upper surface of the mask is smoother than the rough surface before the etch. 
     
     
       22. The method of  claim 21 , wherein etching through at least a portion of the mask includes etching through at least a portion of the mask positioned over the rough upper surface so as to smooth the rough upper surface. 
     
     
       23. The method of  claim 17 , wherein the Fluorine containing gas includes SF 6 . 
     
     
       24. The method of  claim 17 , wherein the component having the formula C x H y F z , is selected from the group consisting of CF 4 , CHF 3 , CH 2 F 2 , C 2 F 6 , C 4 F 6 , and C 4 F 8 . 
     
     
       25. The method of  claim 17 , wherein a molar ratio of Fluorine containing gas to second component in the etchant is in the range of 0.005:1 to 0.25:1. 
     
     
       26. The method of  claim 17 , wherein a molar ratio of Fluorine containing gas to second component in the etchant is in the range of 0.05:1 to 0.15:1. 
     
     
       27. The method of  claim 17 , wherein the etchant includes SF 6  and CF 4 . 
     
     
       28. The method of  claim 17 , wherein etching the optical component precursor includes applying an etchant to the optical component precursor at an RF DC bias power of about 80 W to 200 W. 
     
     
       29. The method of  claim 17 , wherein etching the optical component precursor includes applying an etchant to the optical component precursor at a pressure in a range of 0.1–200 mTorr. 
     
     
       30. The method of  claim 17 , wherein etching the optical component precursor includes applying an etchant to the optical component precursor at a pressure in a range of 1 to 10 mTorr. 
     
     
       31. A method of smoothing a surface on an optical component, comprising:
 forming a mask on an optical component such that an upper surface of the mask is smoother than an upper surface of a medium underlying the mask; and 
 etching through at least a portion of the mask so as to concurrently etch underlying medium and remaining mask, the etch being selected such that a ratio of the medium etch rate to the mask etch rate being in a range of 0.9:1 to 1.1:1. 
 
     
     
       32. The method of  claim 31 , wherein the mask is a photoresist and the underlying medium is silicon.

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